The Early Arab Conquests
Between Muhammad's death and the second fitna, the umma had grown so large that Arabia could no longer be its political center. The Arabian tribes that had carried out the conquests had formed a powerful aristocracy that spread throughout the empire, but their effectiveness as a police force was fatally weakened by their rivalries. The mightiest empires of the Middle East— Byzantium and Persia— were humbled by the Arab warriors of Islam. The umma's government had ceased to be an extension of either Arab tribal democracy or Muhammad's religious prestige; it was firmly grasped by a Meccan mercantile clan based in Syria. The man who saved the umma and the caliphate from anarchy was the Umayyad governor of Syria, Mu'awiya. A more dangerous challenge came from Mu'awiya, 'Uthman's cousin and governor of Syria, whom 'Ali tried to dismiss.